It is known that a self pumping, level regulating device generally of the above described type, as disclosed in principle in, for example, German Patent 11 35 779, especially FIG. 2, can be disposed between two upwardly directed levers that are fixed rigidly on two associated swinging axle halves of a vehicle, in the region of their articulations to the vehicle body. Such a level regulating device functions economically and is quite compact. However, because of the substantial forces involved, and hence the substantial bracing or reinforcing required to accommodate these concentrated forces, the generated effect is such that the vehicle axles have to be of correspondingly large dimensions and strength. Accordingly, with a given material, there not only are correspondingly higher material and processing costs, but also there is a correspondingly increased weight of the axles. This is contrary to the desired energy saving technique of keeping the weight of the vehicle and its individual parts as low as possible. Therefore, while these known devices, typically being integrated as single device, are indeed workable and have their advantages, they at the same time are disadvantageous because of the increased structural strength and weight required of the vehicle parts to which they are connected in order to accommodate the substantial concentrated forces involved.
The present invention is directed to the problem of producing a simple and efficient self pumping, level regulating apparatus or device of the general type previously mentioned, but which is an improvement over known level regulating devices, with retention as much as possible of the advantages of the known devices, especially so that the forces acting on the vehicle axles and other parts will be reduced, so that the axle and such other parts may be kept smaller and lighter.
This problem is solved generally according to the invention in that at least one telescoping spring element is disposed in the region of the vehicle wheels between the vehicle body and the wheel axle, and the pumping and regulating element is disposed separately, advantageously in the mid-zone of the vehicle axle, so as to be acted upon by its spring movement. Because of the improved distribution of forces acting on the axle or other bracing parts in apparatus according to the invention, the forces being distributed over the parts rather than being concentrated, the bracing parts such as wheel axles or the like can be made smaller and lighter. This is practically achieved according to the invention in that instead of a level regulating device of the type used heretofore with integrated telescoping spring element, there is now disposed only the pumping and regulating element, in which the forces that have to be accommodated or braced are relatively minor. The telescoping spring element is separately disposed in the region of the individual wheels, where they evoke significantly less bracing force requirements. Moreover, there is the advantage that a single pumping and regulating element can serve for pressure supply and regulation of a number of hydropneumatic spring elements. Between the individual telescoping spring elements that are acted on by the central pumping and regulating element, there is the possibility of balancing in a known manner by connection of these elements with each other, and by the choke effect thereby occurring in the connecting lines.
The level regulating device or element in accordance with the invention has the further advantage of great economy with retention of the self pumping function, in that the self pumping and the regulation are effected in one and the same element, namely, the pumping and regulating element. Use of level regulating devices that consume supplementary external energy, such as remote-supplied level regulators, is not necessary. All elements of the level regulating device according to the invention can be standardized.
It is known in the art to dispose a telescoping spring element in the region of the vehicle wheels between the vehicle body and the wheel axle in the case of remote-supplied hydropneumatic level regulating devices. In these known level regulating devices, however, there is an extra outlay, because it is necessary to supply supplementary external energy, and to provide a remote feed device and reservoir separate from the regulating element and also extra tubing or piping is required. Furthermore, the regulator must have an adjusting arrangement.
According to an especially preferred form of embodiment of the invention, the pumping and regulating element is actuatably disposed between two upwardly directed levers that are rigidly fixed to two associated swinging axle halves, in the region of the axles' articulation to the vehicle body. In another exemplary embodiment that is also advantageous, the pumping and regulating element is actuatably disposed between the vehicle body and a deflector part that is located on the stabilizer fixed to the vehicle axle, in the middle. The deflector part can be, for example, a bend of the stabilizer, a lever, or the like.
Advantageously, it is also possible to dispose the pumping and regulating element in the middle of a rigid axle, between it and the vehicle body, in an actuatable manner.
According to an especially preferred form of embodiment of the invention, the pumping and regulating element is formed by a cylinder with two end faces, presenting a central pumping chamber with a pump rod therein that issues reciprocably to the outside, and an oil reservoir chamber surrounding the pump chamber. The pumping chamber is connected via an intake conduit and intake valve with the oil reservoir, and is connected with the telescoping spring element via a discharge conduit and discharge valve. The discharge conduit is in open communication with a return conduit running in the partition between the pumping chamber and the oil reservoir, the return conduit being connected to the pumping chamber via first discharge bores disposed advantageously in the mid-zone of the pumping chamber, with which bores there are associated second discharge bores disposed in the partition and connecting the pumping chamber with the oil reservoir, such that the return conduit can be connected with the oil reservoir via the first discharge bores, the pumping chamber, and the second discharge bores. Such a pumping and regulating element is quite simple in construction and function, and is highly reliable. so long as the discharge bores constituting the regulation bores are covered by the pump rod, oil will be drawn from the oil reservoir into the pumping chamber and forced into the hydropneumatic spring element in response to actuation of the pump rod and the cylinder by the spring motions of the axles. When a given oil level or vehicle level is attained, oil will be returned through the discharge bores from the working chamber of the spring element into the oil reservoir of the pumping and regulating element. Thus, there is simple level regulation of the vehicle body.
Advantageously the pump rod is slightly tapered at its free end that is disposed in the pumping chamber, such that the length of the conical end section corresponds substantially to the distance over which the outermost discharge bores are distributed, that is, the distance between the outermost discharge bores. In this manner, there is achieved in a simple way a reduction of the pump output at about the ideal level, and hence a stable regulation.
Preferably there is a gas cushion in the oil reservoir that is under a predetermined base pressure. Thereby provision of a supplementary valve to hold minimal pressure is not necessary.
Preferably the pump and regulating element presents at the outer pump rod end and at the opposite face of the cylinder, elastic bearings for fastening to the adjacent parts of the vehicle. In view of the relatively small external dimensions of the pumping and regulating element, relatively large elastic bearings can be utilized, with their favorable effect on impact.
Other and further advantages and features of the invention will be apparent from the ensuing description of preferred exemplary embodiments that are schematically shown in the appended drawings.